Fig 1: Effects of SIRT1 knockdown on the protection of Sal on ox-LDL-induced HUVECs injury. (A) Cells were pretreated with Sal (0.1, 1, or 10 µM) for 1 h and then stimulated with ox-LDL (100 µg/ml) for 24 h, and the expression of SIRT1 was measured by western blot analysis. HUVECs were pre-transfected with siSRT1 or siControl and incubated with Sal (10 µM) for 1 h followed by treatment with ox-LDL (100 µg/ml) for 24 h. (B) The transfection efficiency was determined by western blot analysis. (C) Cell viability was detected using MTT assay. (D) The LDH release was determined using an LDH assay kit. (E) The apoptosis was detected using the Annexin V-FITC/PI staining kit. (F) Quantitative analysis of Annexin V-FITC(+)/PI(-) and Annexin V-FITC(+)/PI(+). (G) The caspase-3 activity was measured by the caspase-3 colorimetric assay kit. Data are expressed as the mean ± standard deviation; n=3, **P<0.01 vs. the control group; #P<0.05 and ##P<0.01 vs. the ox-LDL group; $P<0.05 and $$P<0.01 vs. the ox-LDL and Sal co-treatment group. si, small interfering; HUVECs, human umbilical vascular endothelial cells; ox-LDL, oxidized low density lipoprotein; FITC, fluorescein isothiocyanate; PI, propidium iodide; LDH, lactate dehydrogenase; Sal, salidroside; NC, not significant; SIRT1, sirtuin 1.